Composition containing blend of acrylonitrile copolymers and chlorine-containing polymer



Unite States tent M COMPOSITION CONTAINING BLEND OF ACRYLO- NITRILE COPOLYMERS AND CHLORINE-CON- TAINING POLYMER Patrick H. Hobson, Decatur, Ala., assignor to The Chemstrand Corporation, Decatur, Ala., a corporation of Delaware N Drawing. Filed Oct. 2, 1957, Ser. No. 687,623 7 Claims. (Cl. 260-455) This invention relates to improved acrylonitrile polymer compositions containing halogen-containing polymers and the invention relates more particularly to intimate blends of fiber-forming acrylonitrile polymers with chlorine-containing polymers, which polymer blends when burned have altered burning characteristics and improved ash formation.

Fiber-forming acrylonitrile polymers which normally contain greater than about 75 percent acrylonitrile have been used extensively in textile applications. Fabric formed from such materials, as is true of most other large volume synthetic polymers employed in textile applications, may be readily burned. When fabrics formed from filaments of acrylonitrile polymers are exposed to an open flame they will burn and globules of molten tarry materials are formed as a product of the combustion. This condition is quite pronounced with fabrics such as non-woven and loosely woven materials. These molten tarry globules constitute hazards in addition to the flame itself of the burning material. For example, these molten tarry materials contain volatile matter and are quite flammable, and in this form have a tendency to run or drip and thus spread the burning material. These tendencies are evident when acrylonitrile polymer fabrics are employed in such articles as awnings, tents, drapes, bed clothing and the like. Another hazard of a burning material which releases molten tarry combustion products is that such materials, upon contact with the skin and hair of mammals, stick and cause severe burns.

Recognizing these tendencies inherent in fabrics and textile materials made from fiber-forming acrylonitrile polymers, it is an object of this invention to provide novel fiber-forming acrylonitrile polymer compositions having altered burning characteristics. it is a more specific ob ject of this invention to provide fiber-forming acrylonitrile polymers which, inthe form of fabric, rugs and the like, when burned, do not produce molten tarry globules as a combustion product, but a firm ash. It is another object of the invention to provide a method to alter the burning and ashing characteristics of fiber-forming acrylonitrile polymers. Other objects of the invention will be apparent from the description thereof which follows The objects of this invention are realized quite unexpectedly by the provision of fiber-forming acrylonitrile polymer compositions containing acrylonitrile polymers of greater than about 80 weight percent acrylonitrile and up to 20 weight percent of other monoolefinic monomers copolymerizable therewith with small amounts of halogencontaining polymers which preferably are polymers containing a major proportion of vinyl chloride and/ or vinylidine chloride. When a flame is applied to such compositions in fabric or pile form, flammability of the acrylonitrile polymer is reduced, the rate of burning is reduced and a firm ash is the combustion product of burning rather than flammable, molten, tarry globules. As a result of the altered burning characteristics of the products of this invention, the potential hazards outlined above of the usual acrylonitrile po ymer based fabricsare not present and the burned fabrics retain their form as a firm ash and molten tarry globules are not produced. These compositions are readily formed into easily processed and dyed filaments which have excellent physical properties.

The halogen-containing polymers found most useful in the practice of this invention are polymers containing a major proportion of vinyl chloride preferably, or vinylidine chloride, which polymers may also contain at most only minor amounts of other monoolefinic monomers containing the C=C groupings which are copolymerizable therewith. Useful polymers or copolymers are those which contain 100 percent vinyl chloride or vinylidine chloride, or copolymers of the two in any proportion, or copolymers of vinyl chloride and/or vinylidine chloride which contain less than 2.0 percent of other copolymerizable monoolefinic monomers including such monomers as vinyl esters such as vinyl acetate; the lower dialkyl esters of maleic and fumaric acid such as the diethyl and dibutyl esters; acrylic and methacrylic acid esters such as methyl acrylate, butyl acrylate, octyl acrylate, methyl methacrylate, butyl methacrylate and the like; vinyl alkyl ethers such as vinyl ethyl ether and vinyl isobutyl ether; isobutylene; isopropenyl acetate; alkyl vinyl ketones; and other monoolefinic monomers which arecopolymerizable with vinyl chloride and vinylidine chloride. More preferred are polyvinyl chloride or copolymers of the nature disclosed above which contain greater than 90 weight percent vinyl chloride and less than 10 percent of other copolymerizable monoolefinic monomers.

The amount of halogen-containing polymer employed in the acrylonitrile polymer composition normally will range from about 5' to about 30 weight percent of halogen-containing polymer based on the total polymer content, and more preferably about 10 to 20 weight percent with a corresponding 90 to weight percent of the acrylonitrile polymer. The amount of halogen-containing polymer to be employed may also be calculated on the basis of total halogen-content of the polymeric composition. In the case of chlorine, the blended polymer compositions ordinarily will contain from about 5 to about 20 weight percent chlorine, and more preferably about 10 to about 15 weight percent.

The halogen-containing polymers which normally will be polymers of vinyl chloride ordinarily will contain a stabilizer, as is well known. Representative stabilizers are dibutyl tin dilaurate, tin mercaptide, epoxidized fatty acid esters, dibasic lead phthalate, lead carbonate, cadmium and barium compounds and the like.

The chlorine-containing polymer is intimately blended with the fiber-forming acrylonitrile polymer by any of the methods known to those skilled in the art. For example the most straightforward method will be to dis-" solve both the acrylonitrile polymer and the chlorine containing polymer in the desired solvent for the acrylonitrile polymer. Quite unexpectedly, the defined acrylonitrile and chlorine-containing polymers in the defined ratios form compatible. mixtures in the solvents set forth hereinafter to provide stable solutions which are useful in large scale spinning operations. Another method is to mix water dispersions of the chlorinecontaining polymer and acrylonitrile polymer, which mixture is then dried and dissolved in the desired solvent. The method employed for obtaining the mixture of the two polymeric materials is not critical so long as an intimate mixture is obtained. I

The acrylonitrile materials which are to be en'tployed taining at least 80 Weight percent of acrylonitrile'inthe polymer molecule and up to 20 Weight percent of mono-i mers copolymerizable therewith; or blends comprising polyacrylonitrile or copolymers comprising acrylonitrile, the blend having an overall polymerized acrylonitrile content of at least 80 percent by weight as will be set forth in more detail hereinafter.

For example, the polymer may be a copolymer of from 80 to 98 percent acrylonitrile and from 2 to 20 percent of another monomer containing the C=C linkage and copolymerizable with acrylonitrile. Suitable monoolefinic monomers include acrylic, alpha-chloroacrylic and methacrylic acids; the methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, methoxymethyl methacrylate, beta-chloroethyl methacrylate, and the corresponding esters of acrylic and alpha-chloroacrylic acids; vinyl chloride, vinyl fluoride, vinyl bromide, vinylidine chloride, l-chloro-l-bromoethylene; methacrylonitrile; acrylamide and methacrylamide, alpha-chloroacrylamide or monoalkyl substitution products thereof; methyl vinyl ketone; vinyl carboxylates such as vinyl acetate, vinyl chloroacetate, vinyl propionate and N-vinylsuccinimide; methylene malonic esters; itaconic acid and itaconic ester; N-vinylcarbazole; vinyl furane; alkyl vinyl ethers; vinyl sulfonic acid; ethylene alpha-, beta-dicarboxylic acids or their anhydrides or derivatives such as diethyl fumarate, diethyl maleate, diethyl citraconate, diethylmesaconate; styrene; vinyl naphthalene; acenaphthalene; vinyl-substituted tertiary heterocyclic amines, such as the'vinylpyridines and alkylsubstituted vinylpyridines, for example, 2-vinylpyridine, 4-vinylpyridine, 5-methyl-2-vinylpyridine, etc., l-vinylimidazole and alkyl-substituted l-vinylimidazoles, such as 2-, 4-, or S-methyl-l-vinylimidazole, and other C=C containing copolymerizable materials.

The polymer may be a ternary interpolymer, for example, products obtained by the interpolymerization of acrylonitrile and two or more of any of the monomers enumerated above. More specifically, a useful ternary polymer comprises acrylonitrile, methacrylonitrile, and 2- vinylpyridine. The ternary polymers may contain, for example, from 80 to 97 percent of acrylonitrile, from 1 to percent of a vinylpyridine or a l-vinylimidazole, and from 1 to 18 percent of another substance, such as methacrylonitrile or vinyl chloride.

The polymer may also be a blend of polyacrylonitrile or an interpolymer of from 80 to 99 percent acrylonitrile and from one to 20 percent of at least one other C=C containing substance copolymerizable with acrylonitrile, with from 2 to 50 percent on the weight of the blend of a copolymer of from 10 to 70 percent of at least one other C=C containing polymerizable monomer. Preferably, when the polymeric material comprises a blend, it will be a blend of a copolymer of 90 to 98 percent of acrylonitrile (more preferably 93 to 97 percent), and from 2 to 10 percent of another monoolefinic monomer (more preferably 3 to 7 percent), such as vinyl acetate, with a suflicient amount of a copolymer of from 10 to 70 percent of acrylonitrile or N-vinylcarbazole and the like and from 30 to 90 percent of a vinyl-substituted tertiary heterocyclic amine, such as vinylpyridine, methyl vinylpyridine or l-vinylimidazole, to give a dyeable blend having an overall vinyl-substituted tertiary heterocyclic amine content of from 2 to 10 percent and preferably about 6 percent, based on the Weight of the blend.

The polymers useful in the practice of the present invention may be prepared by any conventional polymerization procedure, such as mass polymerization methods, solution polymerization methods, or aqueous emulsion procedures. The preferred practice utilizes suspension polymerization wherein the polymer is prepared in finely divided form for immediate use in the fiber fabrication operations. The preferred suspension polymerization may utilize batch procedures wherein monomers are charged with an aqueous medium containing the necessary catalyst and dispersing agents. A more desirable method involves the semi-continuous procedure in which the polymerization reactor containing the aqueous medium is charged 4 with the desired monomers gradually throughout the course of the reaction. Entirely continuous methods involving the gradual addition of monomers and the continuous withdrawal of polymer may also be employed.

The most efiective polymers for the preparation of fibers are those of uniform physical and chemical properties and of relatively high molecular weight. The polymers should have molecular weights of at least about 10,000 and preferably between about 25,000 and 150,000.

In preparing the products of the present invention, conventional equipment ordinarily employed in the manufacture of artificial and synthetic fibers and filaments may be used and particularly the equipment which is usually employed in the manufacture of fibers and filaments from acrylonitrile polymers. The present invention is applicable to the usual methods for forming synthetic filaments and fibers, such as dry spinning and wet spinning.

In the wet or dry spinning process, a solution of acrylonitrile polymer and chlorine-containing polymer, commonly referred to as the dope, is first prepared. Any of the solvents for acrylonitrile polymers may be used in-v cluding N,N dimethylacetamide; N,N dimethylformamide; nitromethane and water; tris(dimethylamido)phosphate; N-nitropiperidine; mixtures of ethylene sulfite with N,N-dimethylacetamide, N,N-dimethylformamide, and nitromethane and water; tri(betacyanoethyl)nitromethane; trichloronitropropanol; mixtures of diethyl phosphate and N,N-dimethylacetamide and N,N-dimethylformamide, and the like; and such solvents as dimethyl methanephosphonate, gamma-butyrolactone, ethylene carbonate and the like.

In the wet spinning process the dope is extruded through an orifice or a plurality of orifices in the face of a spinnerette submerged in a coagulating medium or bath. The bath comprises a non-solvent for the polymer which is also a solvent for or miscible with the solvent in the dope. The coagulating medium or bath will comprise an aqueous solution of a solvent for the polymer being spun, the concentration of the bath being such that the solvent becomes a nonsolvent for the polymer. For example, in the case of amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and the like, an aqueous coagulating bath containing 1 to 75 percent of the amide is satisfactory.

The filaments are moved from the coagulating bath and passed through a washing medium where all residual solvent and coagulating liquid are removed therefrom. Water is the preferred washing medium and is usually contained in a bath through which the filaments are passed. In the bath the washing medium may flow concurrent or counter current to the direction of travel of the filaments therethrough. Washing rolls or like apparatus may also be employed, if desired. Thereafter the filaments are dried and steam stretched, if desired.

In order to orient the polymer molecules in the filaments and particularly if no steam stretch is to be given, they are stretched while in the washing bath or coagulating bath or in both. Further, a solvent stretch bath may be employed immediately following the coagulating bath wherein the polymer molecules in the filaments are oriented. It is to be noted, however, that the conditions of the bath where the stretching is to be done, such as tem perature, size, length of time that the filament remains therein, etc., are regulated as is well known to those skilled in the art. Normally, the solvent stretch or wash bath is maintained at a temperature in the range of to C. and the filaments remain therein for a period less than 15 seconds.

Any solvent for acrylonitrile polymers may be employed in the solvent stretch bath which may comprise a series of stages. The concentration of the solvent in the bath will depend upon the chemical characteristics of the solvent used and the temperature of the bath. Obviously, the concentration must be such that the polymer article passing therethrough will not dissolve therein. Certain solvents may be used in higher concentrations than others. Usually, a solvent stretch bath containing from about to 85 percent solvent by weight, such as N,N- dimethylacetamide, N,N-dimethylformamide, and the like, is satisfactory for the purposes of the instant invention. The bath may contain varying concentrations of solvent at difierent stages during the stretching steps.

The following specific embodiments are illustrative of the improved products of this invention.

Example I A series of spinning solutions or dopes were prepared by mixing together an acrylonitrile polymer-andchlorinecontaining polymers in N,N-dimethylacetamide to a concentration of 18 percent total solids, of which 16 percent was the chlorine-containing polymer, by mixing the ingredients for 45 minutes at 85 C. denier yarns were wet spun in a coagulating bath containing water and a slight excess of N,N-dimethylacetamide and were stretched about 3 times, washed, dride, annealed and crimped 12 to 14 crimps per inch. The acrylonitrile polymer employed in this example was a blend of (A) a copolymer of 94 percent acrylonitrile and 6 percent vinyl acetate and (B) a copolymer of 50 percent acrylonitrile and 50 percent Z-methyI-S-Vinylpyridine, said blend containing 6 percent Z-methyl-S-Vinylpyridine based on the total weight of the blend.

The chlorinecontaining polymers in this examplewere as follows: (1) A copolymer of 95 percent vinyl chloride and 5 percent diethyl maleate (of intrinsic viscosity of 0.85); (2) A copolymer of about 90 percent vinylidene chloride and about 10 percent vinyl chloride; (3') A copolymer of about 80 percent vinyl chloride and percent vinylidene chloride; and (4) A copolymer of about 90 percent vinylidene chloride and 10 percent acrylonitrile. Filaments so produced had tenacity and elongation values as indicated in the table below.

An additional series of spinning solutions were prepared by mixing together the acrylonitrile polymer blend described above in this example and chlorine-containing polymers in N,N-dimethylacetarnide to form a concentration of 18 percent solids of which 10 percent was the chlorine-containing polymers. The chlorine-containing polymers employed were: (5) A copolymer of about 90 percent vinylidene chloride and about 10 percent acrylonitrile; (6) A copolymer of about 90 percent vinylidene chloride and about 10 percent vinyl chloride; and (7) A copolymer of about 90 percent vinyl chloride and about 10 percent vinylidene chloride. The resulting solutions were spun into yarn in the manner described above in this example. The tenacities and the elongations of the yarns may be seen by reference to the table below:

No. Tenacity, Elongation,

gJden. percent 6 Example II 7 Another series of polymeric blends were prepared essentially following the procedure outlined in Example I. Acrylonitrile polymers employed were (1) a copolymer of about 93 percent acrylonitrile and about 7 percent vinyl acetate, and (2) an acrylonitrile polymer blend of (A) a copolymer of 94 percent acrylonitrile and '6 percent vinyl acetate and (B) a copolymer of 50 percent acrylonitrile and 50 percent Z-m'ethyl-S vinylpyridine, said blend containing 6 percent 2-methyl-5-vinylpyridine based on the total weight of the blend. These two acrylonitrile polymers were mixed with 5 and 10 percent of polyvinyl chloride and polyvinylidine chloride in N,N-dimethylacetamide. Films and fibers prepared from these solution blends were burned with an open flame to give in each case a firm ash and molten tarry globules were not formed. In contrast thereto, films and fibers prepared from the above acrylonitrile polymers without the added chlorine-containing polymers burned readily on application of a flame and molten tarry globules were formed.

When the above examples were repeated with the well known fabric flame retarders and fire proofers antimony trichloride, antimony oxide and chlorinated biphenyl in amounts as high as 15 percent in the acrylonitrile polymer dope in place of the chlorine-containing polymers, the amount of molten tar formed when the polymers in fiber and film form were burned was not reduced and burning characteristics of the materials were similar to the unmodified acrylonitrile polymers.

When the above examples are repeated with other acrylonitrile polymers, other halogen-containing polymers, of the nature disclosed herein, and in the amounts set forth hereinabove, similar improvement in the base acrylonitrile polymers as to ash formation on burning are obtained. Such polymeric compositions, including those of the examples, are readily dyed and processed in normal textile operations. The novel products of this invent-ion also may be blended and mixed with other chlorine-free filaments to make improved and useful articles.

I claim:

1. A composition of matter comprising from about to about weight percent of (1) a polymer blend of a copolymer of 80 to 99 weight percent acrylonitrile and 20 to one weight percent of another monoolefinic monomer and a copolymer of 10 to 70 Weight percent acrylonitrile and 90 to 30 weight percent of a monovinylpyridine, said polymer blend having an overall monovinylpyridine content of 2 to 10 percent based on the weight of the blend, intimately blended with about 20 to about 10 weight percent of (2) a chlorine-containing polymer selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, a copolymer of greater than 80 weight percent vinyl chloride and less than 20 weight percent of another monoolefinic monomer and a copolymer of greater than 80 weight percent vinylidene chloride and less. than 20 weight percent of another monoolefinic monomer.

2. A composition of matter comprising from about 80 to about 90 weight percent of (1) a polymer blend of a copolymer of 93 to 97 weight percent acrylonitrile and 7 to 3 Weight percent vinyl acetate and a copolymer of about 50 weight percent acrylonitrile and about 50 weight percent of a monovinylpyridine, said polymer blend having an overall monovinylpyridine content of 2 to 10 percent based on the weight of the blend, intimately blended with about 20 to about 10 weight percent of (2) a chlorine-containing polymer selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, a copolymer of greater than 80 weight percent vinyl chloride and less than 20 weight percent of another monoolefinic monomer and a copolymer of greater than 80 weight percent vinylidene chloride and less than 20 weight percent of another monoolefinic monomer.

3. A composition of matter comprising from about 80 to about 90 weight percent of (1) a polymer blend of a "-7 copolymer of 93 to 97 Weight percent acrylonitrile and 7 to 3 weight percent vinyl acetate and a copolymer of about 50 weight percent acrylonitrile and about 50 weight percent of a monovinylpyridine, said polymer blend havcopolymer of 93 to 97 Weight-percent acrylonitrile and 7 to 3 weight percent vinyl acetate and a copolymer of about 50 weight percent acrylonitrile and about 50 weight percent of a monovinylpyridine, said polymer blend having an overall monovinylpyridine content of about 6 percent based on the weight of the blend, intimately blended with about 20 to about 10 Weight percent of (2) a copolymer of vinyl chloride and vinylidene chloride.

5. A composition of matter comprising from about 80 to about 90 weight percent of (1) a polymer blend of a copolymer of 93 to 97 weight percent acrylonitrile and 7 to 3 weight percent vinyl acetate and a copolymer of about 50 weight percent acrylonitrile and about 50 weight percent Z-methyl-S-vinylpyridine, said polymer blend having an overall vinylpyridine content of 6 percent based on the weight of the blend, intimately blended with about 20 to about 10 weight percent of (2) a chlorine-containing polymer selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, a copolymer of greater than 80 weight percent vinyl chloride and less than 20 Weight percent of another monoolefinic monomer and a copolymer of greater than 80 weight percent vinylidene chloride and less than 20 weight percent of another monoolefinic monomer.

'percent of 2-methyl-5-vinylpyr-idine, said polymer blend having an overall vinylpyridine content of 6 percent based on the weight of the blend, intimately blended with about 20 to about 10 weight percent of (2) polyvinyl chloride.

7. A composition of matter comprising from about to about weight percent of (1) a polymer blend of a copolymer of 93 to 97 weight percent acrylonitrile and 7 to 3 weight percent vinyl acetate and a copolymer of about 50 weight percent acrylonitrile and about 50 weight percent Z-methyl-S-vinylpyridine, said polymer blend having an overall vinylpyridine content of 6 percent based on the weight of the blend, intimately blended with about 20 to about 10 weight percent of (2) a copolymer of vinyl chloride and vinylidene chloride.

References Cited in the file of this patent UNITED STATES PATENTS 2,404,714 Latham July 23, 1946 2,686,169 Ham Aug. 10, 1954 2,688,008 Chaney et al. Aug. 31, 1954 FOREIGN PATENTS 679,562 Great Britain Sept. 17, 1952 OTHER REFERENCES Mason-Manning: The Technology of Plastics and Resins, page 74, published by Van Nostrand C0,, New York, 1945. 

1. A COMPOSITION OF MATTER COMPRISING FROM ABOUT 80 TO ABOUT 90 WEIGHT PERCENT OF (1) A POLYMER BLEND OF A COPOLYMER OF 80 TO 99 WEIGHT PERCENT ACRYLONITRILE AND 20 TO ONE WEIGHT PERCENT OF ANOTHER MONOOLEFINIC MONOMER AND A COPOLYMER OF 10 TO 70 WEIGHT PERCENT ACRYLONITRILE AND 90 TO 30 WEIGHT PERCENT OF A MONOVINYLPRIDINE, SAID POLYMER BLEND HAVING AN OVERALL MONOVINYLPYRIDINE CONTENT OF 2 TO 10 PERCENT BASED ON THE WEIGHT OF THE BLEND, INTIMATELY BLENDED WITH ABOUT 20 TO ABOUT 10 WEIGHT PERCENT OF (2) A CHLORINE-CONTAINING POLYMER SELECTED FROM THE GROUP CONSISTING OF POLYVINYL CHLORIDE, POLYVINYLIDENE CHLORIDE, A COPOLYMER OF GREATER THAN 80 WEIGHT PERCENT VINYL CHLORIDE AND LESS THAN 20 WEIGHT PERCENT OF ANOTHER MONOOLEFINIC MONOMER AND A COPOLYMER OF GREATER THAN 80 WEIGHT PERCENT VINYLIDENE CHLORIDE AND LESS THAN 20 WEIGHT PERCENT OF ANOTHER MONOOLEFINIC MONOMER. 